Performance Analysis of Three Fluid Heat Exchanger Used in Solar Flat Plate Collector System

In the present study, the thermal performance of a three fluid heat exchanger (TFHE) used in solar flat plate collector system is studied. The TFHE is an improved version of double pipe heat exchanger, where a helical tube is inserted between two concentric straight tubes for better performance. This paper presents a new technique of simultaneous air and water heating in TFHE using solar energy. The heating cost can be minimised considerably by supplying the hot water or thermal fluid from a solar flat plate collector through the helical tube of TFHE to heat incoming cold air and water in the inner most pipe and outer annulus. The TFHE is investigated experimentally and validated by comparing the result of experimental approach with literature. Decent agreements between the experimental and literature values are observed. The purpose of this study is to determine the effect of Reynolds number and Dean number on performance of the TFHE in steady-state for both flow configurations. The overall heat transfer coefficients, Uo,h-n varies directly and effectiveness, ɛh-n varies inversely with hot water volume flow rate, however hot water flow rate have least or no effect on coil side Nusselt number, Nuh. The effect of inner Dean Numbers on overall heat transfer coefficients,Uo,h-n and effectiveness, ɛh-n is negligible in parallel flow configuration, however is appreciable in counter flow configuration.ommittee of RAAR 2016.